.backtop {
    position: fixed;
    bottom: 80rpx;
    right: 80rpx;
    height: 80rpx;
    width: 80rpx;
    color: #fff;
    font-size: 70rpx;
    text-align: center;
    line-height: 100%;
    background: #777777;
    border-radius: 100%;

    &:active {
        background: #999;
    }
}